(a) Field of the Invention
The present invention relates to a method and apparatus for generating a signal in a wireless communication system.
(b) Description of the Related Art
A terminal may initially access a wireless communication system, may obtain synchronization, and may demodulate system information, control information, and data information. In this case, sync estimation performance and demodulation performance of the terminal are important indexes that determine the excellence of a system. Accordingly, it is important to efficiently design the sync signal and information signal of a wireless communication system.
In a conventional system for sending information through frequency resources, the sender side allocates a base sequence (i.e., a binary sequence or complex sequence) for synchronization acquisition to available frequency resources and sends a sync signal. Furthermore, the receiver side measures a correlation between the time domain signal of a previously known sync signal and the time domain signal of a received signal and considers sampling timing having the greatest correlation value to be a synch point. However, a conventional method of obtaining synchronization is disadvantageous in that performance is low in an environment in which a frequency offset is great. In order to overcome the disadvantage, the sender side may allocate a specific base sequence to half the available frequency resources, may modify the specific base sequence, may allocate the modified sequence to the other half, and may send a sync signal. However, such a synchronization acquisition method cannot greatly lower a peak to average power ratio (PAPR) due to its inherent limit.
Although the receiver side has accurately obtained synchronization, it must be able to properly demodulate system information, control information, or data information. Accordingly, the receiver side must be able to obtain a diversity gain even in a fading channel and to lower the PAPR. A technology for lowering the PAPR must be able to be applied to all the transmission signals because it may help in reducing the cost of an amplifier that may be mounted on a terminal. The reason for this is that if any one of transmission signals has a high PAPR, the receiver side must use an expensive amplifier in order to prevent inherent distortion attributable to the signal having the high PAPR, thereby increasing the amplifier cost.